Engine components exposed to the hot combustion gas flow of combustion turbine engines may be formed of a ceramic refractory material. A ceramic matrix composite (CMC) lamellate wall structure with a high temperature ceramic insulation coating, commonly referred to as friable grade insulation (FGI), is described in commonly assigned U.S. Pat. No. 6,197,424. Current materials of this type provide strength and temperature stability to temperatures approaching 1700° C. Cooling of such structures is generally limited to back side air impingement cooling.
Future combustion turbine designs are expected to require ever increasing firing temperatures that may exceed the operating limits of such designs. An actively cooled CMC wall structure is described in commonly assigned U.S. Pat. No. 6,746,755 where cooling tubes are disposed between the layers of CMC material. Further improvements to permit operation at even higher temperatures are desired.